Most modern automotive fuel systems utilize fuel injectors to deliver fuel to the engine cylinders for combustion. The fuel injectors are mounted on a fuel rail to which fuel is supplied by a pump. The pressure at which the fuel is supplied to the fuel rail must be metered to ensure the proper operation of the fuel injectors. Metering is carried out using pressure regulators that control the pressure of the fuel in the system at all engine r.p.m. levels.
Fuel flow rate, measured in liters per hour, through known pressure regulators tends to be low at high engine speed, measured in revolutions per minute, as large quantities of fuel are consumed in the combustion process. At low engine speeds, less fuel is consumed in combustion and flow rates through the pressure regulators are high. These high fuel flow rates can produce unacceptably high noise and pressure levels.
A first known pressure regulator, as shown in FIG. 7, includes a spring biased valve seat with a longitudinal flow passage. The longitudinal flow passage, which has a constant cross-section orthogonal to a longitudinal axis, can be modified for length along the longitudinal axis to slightly modify noise and flow performance characteristics.
A second known pressure regulator, as shown in FIG. 8, includes a necked-down longitudinal flow passage and mutually orthogonal cross-drilled holes. The cross-drilled holes disperse fluid flow in a manner that is effective to improve the noise and flow characteristics of the known regulator shown in FIG. 7. However, manufacturing a seat with the necked-down longitudinal flow passage and cross-drilled holes is costly to machine.
It is believed that there is a need for a pressure regulator that is less expensive to manufacture and maintains flow-related noise and pressure within acceptable levels, even at high fuel flow rates.